The Problem with High-PPI Windows Display Scaling

High-resolution screens are getting more and more common. You can get a pretty good 27-inch 2560x1440 screen for $300, and cheap 4K displays are on the horizon--although you shouldn't actually buy one yet. And of course there's all those 13-, 14-, and 15-inch laptops with high-resolution screens, from 2560x1440 screen available on the Acer Aspire S7 and Toshiba Kirabook, to the 3200x1800 displays on the Samsung Ativ Book 9 Plus and Lenovo Yoga 2 Pro. And, of course, the Retina MacBook Pro, the granddaddy of the genre, with its 2560x1600 13-inch and 2880x1800 15-inch form factors.

These high-res ultrabooks are beautiful when they work properly, but I don't think you should actually buy one. Especially not one to run Windows desktop applications.

At 27 inches, a 2560x1440 display is amazing, because you can use it without scaling the Windows UI at all. You can comfortably fit two 1280px-wide windows side-by-side, which means you can get the benefit of two smaller monitors in one. Here's what that looks like. There's so much room for activities!

But that's 2560x1440 at 27 inches, or about 109 pixels per inch. Cramming the same number of pixels (or more!) into a 13.3-inch screen ups your pixel density to 221PPI. It's a much sharper image, but if you leave Windows display scaling at 100%, the desktop user interface becomes unbearably tiny--just look at those taskbar icons.

Here you can see two 2560x1440 screens at 100 percent scaling. The top screen is 27 inches, and the bottom is 13.3. One is usable, the other is for leprechauns with LASIK. So what do you do? Scale it up, of course.

The Problem with Windows Display Scaling

Windows 8.1 has the best display scaling support of any version of Windows so far, and it's accessible right from the Display settings in your control panel. By default you can set scaling to 100%, 125%, 150%, or 200%--that'll keep your screen resolution the same, while resizing the deskop UI elements so they're usable.

The first problem with small high-DPI screens is the same problem with low-resolution screens: lack of screen real estate. A 2560x1440 screen with 200% UI scaling has the same effective screen area as a 1280x720 panel, which is to say not much. Of course, everything ought to be much sharper, since you have four times the number of pixels to use in the same space.

This is what the Retina MacBook Pros (Macsbook Pro? Macbooks Pro?) do: the 13-incher runs at an effective 1280x800 by default, and everything just looks clean and sharp. So you'd think Windows could manage.

Most of the Windows UI scales just fine, but some bits don't scale at all, appearing at 100% even if the rest of the UI is at 200%.

If Windows scaling worked perfectly, there's just not a lot of screen real estate if you're scaling everything up 200%. That's fine if you only want to do one thing at a time, but I'm used to using two side-by-side windows for my work: one for research, and one for writing. You just can't do that at 200% scaling on a 13.3-inch screen. You can do it at 100% scaling, but then everything's unusably small. No bueno. No point-o.

Alas, Windows doesn't scale perfectly. Most of the Windows UI scales just fine, but some bits don't scale at all, appearing at 100% even if the rest of the UI is at 200%.

And applications, well. That depends on the app.

Chrome is a particularly bad example, despite Google themselves shipping a Chromebook with a 2560x1700 screen. Here's Chrome and Firefox side-by-side on a 2560x1440 Asus Aspire S7-392, with Windows scaling set to 200%. Notice how much cleaner and smoother the text is in Firefox (on the right).

Click to enlarge.

You can force apps to use their built-in high-DPI scaling modes, if they have them, rather than Windows' scaler, by using Windows compatibility settings and, in the case of Chrome, first enabling the "Touch Enabled UI" in chrome://flags and then increasing the default page zoom. (The HiDPI flag doesn't work well). Now web pages themselves look good and are scaled correctly, but the Chrome UI--tabs, favicons, extensions, the menu bar--are tiny, while the tab titles (drawn by the Windows scaler) are twice the size they should be. Here's Chrome with its experimental HiDPI mode turned on, on the left:

Honestly, if you have a high-res display you're better off using Firefox than Chrome, at least until they get their high-DPI support in order.

The Solution?

So what's the solution here? As Norm discovered when he reviewed the Lenovo Yoga 2 Pro, the sweet spot for these high-res ultrabooks seems to be 150 percent scaling. A 3800x1800 screen like the Yoga 2 Pro has, at 150% scaling, an effective screen size of 2533x1200--plenty of space for multiple windows simultaneously while still being mostly large enough to read text.

That's not the case with lower-res high-DPI screens, though--a 2560x1440 screen at 150% scaling gives you an effective screen area of 1706.67x960--barely better than a 1600x900 screen, and not enough to display two full web pages side-by-side if they're not context-aware. At least you don't have to worry about dithering or jagged edges just because you're scaling to a non-integer pixel multiplier. But given the problems with Windows DPI scaling, there's no point in buying a high-res screen just to scale it back down.

You could also set your screen resolution to 1920x1080 and just run at 100% scaling, but since that's not the screen's native resolution, it's not going to look as good as a 1080p screen running at 1080p, where every pixel displayed maps perfectly to a physical pixel.

1080p is right for me

This is why, for the time being, I think 1920x1080 is the perfect size for 13.3-inch laptop screens. Its resolution is high enough (165PPI) that you aren't distracted by visible pixels, there's enough screen space to snap two windows side-by-side and still fit full web pages in each, and since you're running at 100% display scaling everything just works. Anything lower-res starts looking bad and compromising on screen real estate, and (for now) anything higher-res starts...looking bad and compromising on screen real estate.

High-DPI screens still make sense on larger desktop monitors, as long as they're physically large enough that you can use them without scaling.

High-DPI screens still make sense on larger desktop monitors, as long as they're physically large enough that you can use them without scaling. A 27-inch 2560x1440 screen is perfect for desktop use. 27- and 30-inch 4K screens will be good too, once there's one worth buying.

Until Windows and the apps that run on it catch up and display scaling works perfectly across the board, the best way to deal with it is to avoid it entirely, by using a screen resolution appropriate to the panel size and not using display scaling at all. So go for a 1080p screen on that next ultrabook you buy. You'll save some money and you'll have a better experience.

Unless getting the high-res panel is the only way to get a good IPS display. Then you should spring for it. Weird scaling on IPS is better than perfect performance on TN.

Do you have a high-resolution display? What do you use it for? What little tips and tricks do you use to make it more workable?